Passivhaus overheating shouldn’t happen: it’s one of the criteria of the international Passivhaus standard.

Even so, people sometimes ignore this requirement during the early stages of the design process.

It shouldn’t be ignored. Overheating is a key design issue and should be addressed from the beginning as an integral part of the Passivhaus design process.

But how?

This blog post is a simple guide to preventing Passivhaus overheating by design.

047 Passivhaus Overheating Design

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Energy efficiency is easier at large scale.

This is also true of the international Passivhaus Standard – it is relatively easy for a large building to meet the requirements compared to a smaller building. The heat loss form factor is part of the reason why this is the case. A large building tends to have less surface area to lose heat relative to the internal volume.

Airtightness is another reason. As this is measured in air changes per hour for Passivhaus, a large building has a large air volume. Achieving 0.6 ach with a large air volume isn’t as demanding as achieving it with a small air volume. It’s still an exacting target to meet, though.

However, the total energy consumption of an energy efficient large building might still exceed the total energy consumption of a smaller less efficient building. For this reason and others, constructing smaller buildings is important in the Anthropocene. We must radically reduce the total amount of CO2 being emitted.

Some people are responding to this by designing and constructing ‘Tiny Houses‘. The houses in this growing movement are around 45m2 or less and often on wheels.

Is it possible for a ‘Tiny House’ to meet the Passivhaus Standard?

Yes, it’s possible to construct a Passivhaus Tiny House – this blog post features three examples. The examples come from the United States, Australia and France and all take unique approaches.

Passivhaus Tiny House: not only is it possible, it’s happening.

046 Passivhaus Tiny House
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This blog post is a review of the 3rd, revised edition of “Details for Passive Houses: A Catalogue of Ecologically Rated Constructions” published in 2009. This book is edited by the IBO, the Austrian Institute for Healthy and Ecological Building. It is a large and hefty hardcover tome at 3.2 x 24.8 x 35.6 centimetres.

People often ask if there is a catalogue of suitable details for Passivhaus construction. There isn’t one, at least not in English, that I am aware of. Of course, this might be because it is possible to build a Passivhaus with almost any construction system, so such a catalogue would be a huge undertaking. However, this book is the closest thing there is to such a catalogue.

The purpose of “Details for Passive Houses: A Catalogue of Ecologically Rated Constructions” is twofold; to provide an ecological evaluation of a range of Passivhaus-suitable construction details and to suggest alternatives that “illustrate the possibilities and limitations of ecologically motivated material selections.

The book contains 130 Passivhaus construction details, with assembly cross-sections and junction details. The details are beautifully illustrated to scale in four colours throughout.

Details for Passive Houses: A Catalogue of Ecologically Rated Constructions” is an excellent reference for successful Passivhaus construction detailing.

Successful Passivhaus Construction Details Cover

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This is a Passivhaus Basics blog post that gives an overview of a specific aspect of the Passivhaus Standard.

The international Passivhaus Standard is a clearly defined and rigorous standard for energy efficiency, comfort and quality assurance of buildings. Designing a building to achieve the standard requires detailed knowledge and a rigorous methodical approach to design and documentation. To ensure this happens, it is possible to train and qualify as a Certified Passivhaus Designer or Consultant.

The route to certification is the same for a designer or a consultant. It is only the individual’s prior qualifications and experience that determines if they qualify as one or the other. For clarity, this post will only refer to a Certified Passivhaus Designer, but for all intents and purposes, ‘designer’ is interchangeable with ‘consultant’ in this context.

A Certified Passivhaus Designer, regardless of their prior qualification, works across disciplines on a Passivhaus project. Their role integrates architecture, structure, building services, building science, energy modeling and construction detailing. They will at times both support and challenge the other designers on a Passivhaus Project.

The Certified Passivhaus Designer on a project doesn’t need to be completely independent. They can also be the architect, structural engineer, building services engineer, or another consultant on the team. And the same person fulfilling two roles does have advantages. However, in many cases combining two roles requires more time and work than one individual has available. Regardless, it is best if the Certified Passivhaus Designer is an integral part of the design team rather than just an occasional consultant.

The Passivhaus Building Certifier must be independent of the design team.

A Certified Passivhaus Designer brings the detailed knowledge and rigorous methodical approach needed to design buildings to the international Passivhaus Standard.

043 What is a Passivhaus Designer

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Design and build procurement routes have been particularly popular in the UK for large scale Passivhaus projects. Clients, often public bodies, want the benefits that Passivhaus brings, but are wary of the delivery risks in a relatively immature Passivhaus market. Using a design and build procurement route allows the client to pass the majority of the risks to the contractor. The client may pay a higher price for this, but theoretically, it offers more certainty of cost and time.

However, using a design and build procurement route can offer the greatest potential for an integrated design approach. And this is beneficial for a Passivhaus building project. When it is done right, the full design and construction teams can collaborate to develop a highly integrated solution. Unfortunately, when not done right, design and build procurement can conflict with an integrated design approach.

This blog post looks at three situations where design and build procurement can conflict with Passivhaus;

  1. Design scope mismatch
  2. Consultants timelines out of sync
  3. Tender design overconstrained

These situations can cause issues with any building project and may increase costs and delivery time. For a Passivhaus building project, these situations may additionally jeopardise achieving the standard.

Passivhaus design and build procurement: avoid situations that conflict with an integrated design approach.

Procurement Conflicts with Passivhaus

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